The present invention relates to a laser beam detecting device for detecting a laser beam emitted from a laser beam generator such as a rotating laser which is used in a land formation work or the like.
A laser beam detecting device is installed in the vicinity of a leveling implement of a construction machine. Therefore, wiring which uses cords is an obstacle to the installation of the laser beam detecting device. Moreover, it is very dangerous to be caught by the leveling implement and therefore, for avoiding such a danger, it is necessary to exercise a great care in installing the laser beam detecting device. Thus, the work for installing the laser beam detecting device has so far been very troublesome.
For dispensing with such cords it has been proposed to drive the laser beam detecting device with a battery.
If the laser used is kept in operation, the battery will soon run down.
In the conventional laser beam detecting device, for avoiding such an inconvenience, the operation of a power supply for the entire device is switched over between ON and OFF, depending on whether a laser beam is incident or not.
In this case, if a predetermined time elapses in the absence of a laser beam, the operation mode of the device becomes xe2x80x9csleep modexe2x80x9d and the device stands by. When a beam sensor used in the laser beam detecting device detects a laser beam in the sleep state, the sleep mode is canceled and the laser beam detecting device assumes an operating state.
The conventional laser beam detecting device which detects the incidence of laser beam is required to be always in a state capable of detecting a laser beam. That is, the beam sensor must be kept ON.
However, since the beam sensor has a function of detecting a laser beam incidence position, it is provided with an analog circuit having many channels, resulting in power consumption as much as about five-sixths of that of the device.
Thus, even in the sleep mode, a power saving effect cannot be expected so much; that is, the consumption of the battery used has not been reduced so much.
It is an object of the present invention to realize a high power saving characteristic.
This object can be achieved by a laser beam detecting device described herein.
The laser beam detecting device according to the present invention detects a laser beam which is emitted from a laser beam generator and which forms a reference plane. A beam sensor used in the laser beam detecting device for detecting a laser beam is connected to a power supply. When a construction machine with the laser beam detecting device attached thereto is not in operation, the power supply is turned OFF automatically. Upon re-operation of the construction machine, vibration of the construction machine is detected by a vibration sensor, thereby tuning ON the power supply for the beam sensor.
Preferably, the vibration sensor is constituted by a chip capacitor.
In a preferred mode of the present invention, the power supply for the beam sensor is controlled by a microcomputer and the state of operation of the construction machine is detected by the vibration sensor.
With this configuration, not only the cancellation of a sleep mode can be controlled positively by the operation of the construction machine to which the laser beam detecting device is attached, and not by incidence of a laser beam, but also in the sleep mode it is possible to stop the supply of electric power to the beam sensor, that is, the supply of electric power to only the vibration sensor suffices, thus permitting a remarkable reduction of power consumption.
A laser beam detecting device in a preferred mode of the present invention is fixed to a predetermined position of, for example, an arm of a construction machine such as an excavator through a magnet or a clamp. The predetermined position as referred to herein indicates a position which permits an offset to be clarified between a leveling implement (especially a tip end thereof) such as a bucket which forms a working surface and the predetermined position.
In a working site, a reference plane is formed with a laser beam emitted from a laser beam generator such as a rotating laser.
The laser beam detecting device is mounted above the leveling implement of the construction machine so that a reference position is established at a predetermined height with respect to a portion of the leveling implement which portion forms a working surface.
In the laser beam detecting device, a laser beam is detected by the beam sensor, and in accordance with a deviation (in the vertical direction) between an incidence position of the laser beam and the reference position of the device, the direction in which the leveling implement is to be moved is instructed to an operator of the construction machine on a display (display portion).
In a laser beam detecting device according to a more preferred embodiment of the present invention, the beam sensor is mounted above the leveling implement, a laser beam as a reference is detected by the beam sensor, and information based on the beam detection is displayed on a display.
A plurality of reference positions are established in a detection range of a beam receiving portion of the beam sensor and one of the reference positions is made a standard position, while the other reference positions are made offset positions. First and second offset positions are established respectively above and below the standard position. There is provided a display (display portion) indicating in which of standard and offset positions the laser beam detection is being conducted.
In the beam sensor used in the laser beam detecting device, an incidence position of a laser beam with respect to a reference position (height indication) is detected, and on the basis of the detected beam incidence position, the direction in which the leveling implement is to be moved, as well as the distance at which the leveling implement is to be moved, are indicated to the operator.
The laser beam detecting device is attached, at the back of its body, to a predetermined position (e.g., arm) of the construction machine removably with screws or the like.
Alternatively, the laser beam detecting device may be fixed magnetically to the leveling implement of the construction machine. In this case, a strong magnetic force can be obtained by holding plural magnets in between plural net plates. In this case there is attained a high durability because the net plates are in contact with the leveling implement. Besides, since the net plates are each adapted to move slightly, they can fix the magnets securely and prevent them from coming off even if the magnet surfaces are somewhat uneven or even under an abrupt shock.
The laser beam detecting device may also be fixed to a pole or the like which is fixed to the leveling implement. In this case, a clamp is often used for the fixing.